What are VSDISCO files ?

VSDISCO files are DISCO files that enable dynamic discovery of Web Services. ASP.NET links the VSDISCO to a HTTP handler that scans the host directory and sub-directories for ASMX and DISCO files and returns a dynamically generated DISCO document.

What is Webservices

Web services are programmable business logic components that provide access to functionality through the Internet. Standard protocols like HTTP can be used to access them. Web services are based on the Simple Object Access Protocol (SOAP). Web services are given the .asmx extension .We have to use the standard to wrap up a call to a Web service is HTTP with SOAP.

What is Sealed class ?

A class can be made sealed in c# using the sealed keyword. Sealed means that the class cant be inhereted. You can extend this functionality to the individual methods as well. In case you want a class to be inhereted, excluding one of its methods, just make that particular method sealed.